The present invention relates generally to boat trailers and more particularly to a boat trailer with conformable and adjustable supporting apparatus for minimizing stress on the boat hull carried thereby and for ease of loading and unloading.
Because the hull shapes of boats can be quite varied and different in design, a problem has existed for boat trailer manufacturers to provide a trailer which is adaptable to transport boats of different sizes and shapes of hulls. Along with this, of primary importance is the ease of loading and unloading a boat from the trailer.
It has been well known that the use of rollers on the rear end of a boat trailer aids and facilitates the loading and unloading of a boat from the trailer by reducing the friction between the boat and the trailer. These rollers in the past have been made adjustable to conform somewhat to the particular boat being loaded on the trailer by being pivotably mounted on the trailer frame.
While it has generally been known that the use of rollers and roller trucks which are adjustable in both the vertical and horizontal direction will enhance the versatility of a boat trailer for handling a plurality of different boat hull designs and sizes, improvements continue to be developed wherein the improved designs better conform to boat hull configurations.
Johnson, U.S. Pat. No. 3,155,249 has taught a boat trailer with longitudinal fulcrumed levers pivotable in a longitudinal plane of the trailer. These levers carry roller trucks which are pivotable in a transverse plane to the longitudinal axis of the trailer. The roller trucks therefore are capable of dropping down during loading and unloading of a boat from the trailer as the levers pivot, and also independently pivoting at an angle in transverse plane to conform to the hull shape of the boat loaded thereon.
Flachbarth et al, U.S. Pat. No. 3,403,798, teaches a pair of longitudinal members positioned on a cross support at the rear of the trailer, each of these longitudinal members being pivoted in the middle of its length to act as a lever. These members tilt to aid in loading and unloading of a boat and operate in conjunction with a centrally fixed keel roller.
Calkins, U.S. Pat. No. 3,512,667, teaches a boat trailer having at least one U-shaped hull support cradle. This U-shaped structure is pinned to the side rails of the trailer for pivoting in a longitudinal plane. The back end of this cradle carries a roller on each end which is pivotable in a transverse plane.
Johnson, U.S. Pat No. 3,756,439, teaches boat trailer supports pivotable in both the longitudinal and transverse planes about separate pivot points and having a transverse support bar for maintaining the alignment of the boat hull support rollers.
Calkins, U.S. Pat. No. 3,785,677, provides a boat trailer with U-shaped support cradle carrying a plurality of rollers at both the front and back ends thereof. The rear rollers are pivotable in a transverse plane. The cradle is self-balancing for even distribution of weight forces on a boat carried thereon.
Rogers, U.S. Pat. No. 3,812,986, provides a boat trailer having at least one C-shaped or U-shaped pivotable carriage with a plurality of roller trucks thereon. Each roller truck includes a fulcrumed lever bar which is slightly curved into a handle-bar shape.
Cox, U.S. Pat. No. 3,888,367, provides a boat trailer having a plurality of roller trucks pivotable in transverse planes, said roller trucks being in a "H " configuration of four rollers each.
Moore, U.S. Pat No. 3,892,320, provides a boat trailer with multiple rocking boom suspension. This trailer has roller trucks in sets of four rollers. A pair of rollers are mounted, one at each end of a U-shaped bar. Each U-shaped bar is mounted on an individual one rectangular solid rod. The rods are clamped together in pairs to configure a four roller "H" configuration truck. An adjustment can be made on the spacing of the U-shaped bars by sliding the adjacent rectangular rods together or apart from one another.
Godbersen, U.S. Pat No. 3,917,087, provides a boat structure where the rear horizontal cross member itself is pivotable to aid in loading and unloading of a boat hull.
Ullman, U.S. Pat No. 3,974,924, provides a boat trailer having a compound cantilevered stern and loading subframe on a rigid structural cross member.
Johnson, in U.S. Pat No. 4,196,502 and U.S. Pat No. 4,210,235, provides two variations of a roller configurations where the roller itself is permitted to wobble or move in a 360 degree orientation to the shaft upon which it is mounted. This wobble is facilitated by a hemispherically shaped bearing surface which is a part of the roller and the surface upon which the roller is caused to rotate.
Johnson, U.S.at No.4,278,388, provides a trailer having a truss type winch support and a stern end roller truck structure mounted to a subframe where the main crossbar support itself pivots about an axis positioned below the main structural side rail of the trailer.
An object of the present invention is to provide a boat trailer of a design which is conformable to various boat hull shapes and sizes and which allows for a plurality of adjustments of various of its members including position and angle.
A second object of this invention is to provide such a boat trailer where the structural members are of reduced weight while maintaining the necessary strength for the desired function.
An additional object of this invention is to provide such a boat trailer where its structural members are of a design which is economical to manufacture.
A further object of this invention is to provide such a boat trailer with a winch stand which is variably positionable on the trailer frame and which is adjustable as to the height of the winch.
A further object of this invention is to provide such a boat trailer with hull support roller trucks which pivot in a longitudinal plane on a subcarriage support member.
A further object of this invention is to provide fulcrumed roller support levers of reduced mass and weight and enhanced strength, these support members providing an adjustment for varying the distance between roller pairs.
An even further object of this invention is to provide articulated rollers which wobble or change orientation on their support.
An additional object of this invention is to provide such articulated rollers wherein the wobble permitted in one plane is greater than the wobble in the second plane.